The major thrust of the work to be carried out under this project is to prepare penta and hexacoordinated compounds of phosphorus that possess novel structures. These materials will be prepared by known procedures and new methods for their preparation will also be sought. The substances prepared under this project will be submitted for testing for antitumor activity by NCI. Once prepared these materials will be subjected to extensive physical and chemical investigation. The prime goal of this phase of the project is to determine those factors which contribute to the stabilization of these substances and where it occurs those factors which control the rates of intramolecular ligand reorganization "pseudorotation". Another area to be investigated is studies of the utility of P (V) compounds to act as synthetic reagents.